Exchanged messages are treated in conventional email systems similar to regular mail. This data model addresses single, standalone, one way communications effectively. However, increasingly email is no longer standalone, or simple one way communication. A given email is now often part of a large protracted “conversation”, an interrelated series of messages that, when viewed over time and in aggregate, more closely resembles an interactive discussion between people and groups.
While some indication of reply and/or forwarding relationship between messages may be provided in conventional systems, the user interfaces do not typically present the user a visually user-friendly representation of the messages in an email trail or conversation with their relationships that includes an intuitive way for an e-mail user to read and interact with an e-mail conversation of random complexity.
E-mail conversations are logically formed by e-mail messages linked to each other via an in-reply-to relationship. Typically, a sender sends an original e-mail to a set of recipients, which may reply to that message and then to subsequent replies thus building a conversation (a tree of e-mail messages, effectively). Building a user interface to display all these messages and their in-reply-to relationships is not an easy task, especially as the number of multiple replies to the same message increases (also called “branch points”) and the conversation becomes less linear.